Comment by caspper69

I agree with you 100%. I think arenas are a much lighter burden for the programmer to reason about than lifetimes & access patterns.

But arenas can have one big drawback, and that is if you do a lot of allocations and deallocations, especially in long-running routines, you can essentially leak memory, because arenas are not usually freed until they are going out of scope. This can vary depending on the language and the implementation, though.

My thought to counteract that though is you could offer a ref-counted arena just for this scenario, but I'm not sure what exactly that would look like (automatic once refs hit 0? offer a purge() function like a GC?). I haven't wrapped my head around the ergonomics yet.